The proposed work is derived from a general interest in the adaptive characteristics of rapid eye movement (REM) sleep. Specifically, the following strategies and questions are utilized: (1) What is the relationship between the presleep situation (e.g., general or specific presleep task) and dream content? How is this relationship modified by presleep personality and presleep mood estimates? (2) What is the relationship between certain kinds of presleep event incorporations in the dream and changes in behavior (e.g., mood, performance, etc.)? How are these relationships modified by personality and by specific type of presleep "problem" (e.g., convergent vs. divergent task requirement)? What are the implications of such relationships to the general hypothesis that dreaming is or can be an adaptive process (i.e., promoting positive changes). (3) In what way does REM deprivation affect postsleep behavior? How is such a relationship modified by (a) individual differences, (b) type of behavior, (c) method of REM deprivation? What are the implications in these relationships for the following questions: (a) Are there individual differences in the "need" for REM sleep? (b) Does waking fantasy "substitute" for lost REM? (c) What kinds of "problems" are most susceptible to REM sleep information processing? (4) What is the relationship among REM pressure (REM latency), REM density, and REM duration (REM "rebound"), and how are each related to individual differences and behavior? (5) How does REM dream content change across REM periods of a night? How are these changes related to concomitant changes in other REM characteristics such as eye movement and EEG? What are the implications of such changes, and individual differences in these changes, for the hypothesis that there is a gradual change in the relative dominance of the left vs. the right hemisphere during sleep from REM to REM period?